Radio 4's The World This Weekend canvassed the views of more than 100 backbench Conservative MPs - 25 said they plan to vote against the bill and another five said they would abstain.

But shadow transport secretary Mary Creagh confirmed Labour would be backing the government.

"With the costs going up we had to look again at it, we had that look and we're backing the project," she told Sky News.

"There are a lot of my Shadow Cabinet colleagues where it goes through their constituencies and they are absolutely right to raise those local issues.

"The Phase Two route consultation closed in January, we've got to see what changes, if any, there are to that route and the government needs to get on and spell out what they are."

'Sympathetic route'

She added: "We've got to invest in our transport infrastructure but we've got to keep costs under control as well."

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Michael Fabricant was sacked as Conservative vice-chairman over his views on HS2

Former Conservative Whip Michael Fabricant said he knew between 80 to 100 of his fellow MPs have "really serious doubts" about HS2 but were reluctant to take on the government as it was expected to clear its second reading.

He told Sky News said: "If Labour was against it then the rebellion would be a lot bigger than 40."

Mr Fabricant is among the senior Tories who have tabled amendments in an attempt to block the government's plans.

He wants the coalition to bring forward a cheaper and more environmentally "sympathetic" route.

Former Wales secretary Cheryl Gillan has tabled a cross-party amendment to block the Bill and vowed to vote against the second reading.

'Rubbish'

She said: "There is no doubt that with all three parties whipped to support HS2, there is no chance to stop it.

"But I have to register opposition on behalf of the many people who do not want this project."

Ms Gillan said she was disappointed the government had not listened to demands to allow an open-ended Commons debate on Monday.

MPs will be given an extra 60 minutes, compared to the usual arrangements on a Monday, to raise objections.

But Ms Gillan said rebels "may have as little as 10 minutes to put across our arguments".

"For a government that wants to be transparent and bring people along with them, the right thing would be to allow a full debate. This is rubbish," she added.